This invention relates to a coining press having a machine frame, a coining drive for slides and coining dies, an ejector coining die, against which the coining die can be pressed with the interposition of the coining blank and, for this purpose, is partially yielding, a drive for the ejector movement of the ejector coining die and one device respectively for feeding the coining blank and for removing the finished coined part.
A coining press of this general type is known from European Patent Document EP-A-0 101 590. In the case of the coining press disclosed in the above-mentioned document, the coining drive takes place by means of a triangle lever which is known per se, is driven by a crankshaft by way of a center bearing and which, by means of its rearward link bracket, is pivotally connected to a control arm and, by way of this control arm, is pivotally connected on the frame side to the slide by means of its forward link bracket by way of a pressure rod. This vibrating system is constructed such that centers of rotation and pivots in their positions with respect to one another permit at least an approximately circular movement for the pressure rod in its center of rotation on the slide at the point in time of its travelling through the rearward dead center.
By means of the above-mentioned arrangement, it is possible to control the linear movement of the slide in such a manner that sufficient time remains in order to remove a coined coin from the coining tool and to insert a new coining blank between two coining operations.
However, in the case of the known coining press, it is a disadvantage that the described coining drive requires a relatively large amount of space, particularly if it is to be used in presses which are to apply pressures of more than 200 t (metric tons) to the coining blank. Since these forces also affect the coining drive, the individual components of the coining drive must be constructed to be correspondingly stable so that the individual components must be provided in relatively large sizes.
Another disadvantage of the known coining press is the relatively large play within the coining drive which results from the large number of joints used.
It is therefore an object of the present invention to eliminate the present disadvantages of the prior art and particularly to provide a coining press which has an overall height which is as low as possible and which has a lower play within the coining drive.
According to the invention, this object is achieved by providing a coining press having a machine frame, a coining drive for slides and coining dies, an ejector coining die, against which the coining die can be pressed with the interposition of the coining blank and, for this purpose, is partially yielding, a drive for the ejector movement of the ejector coining die and one device respectively for feeding the coining blank and for removing the finished coined part, wherein the coining drive is a coupling dwell gear which is hinged to a toggle joint gear, the coupling dwell gear having a connecting rod moved by an eccentric shaft, the longitudinal shaft of the connecting rod substantially largely in parallel to the coining plane and the end of the connecting rod facing away from the coining die being hinged to a booster device, the toggle joint gear having three pressure lugs which, on one end respectively, are hinged to one another on a pin, while the end of a first pressure lug is hinged to the connecting rod, and wherein the other end of a lower pressure lug is hinged to the machine frame and the other end of an upper pressure lug is hinged to the slide.
By providing a coupling dwell gear which has a booster device, a toggle joint gear can be controlled in a simple manner which, in comparison to the toggle joint gear of the prior art, has a much lower overall height because the triangle lever used in the prior art is omitted so that the whole coining drive and therefore also the coining press itself has a lower overall height.
Another advantage of the coining press according to the invention is the reduction of the play of the coining drive because this coining drive has significantly fewer joints than in the case of the known coining presses so that the overall play is reduced which is composed of the play in the individual joints. This reduction of play has a positive effect particularly in the case of frequent load changes which occur in the case of high-speed coining presses.
In addition, because of the combination according to the invention of a coupling dwell gear and a toggle joint gear, a lower eccentricity of the eccentric shaft, which drives the connecting rod of the coupling dwell gear, is required. This results in the advantage that a smaller and therefore lower-cost coupling may be provided between the eccentric shaft and the drive for the eccentric shaft so that the manufacturing costs for the coining press are lower.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.